Refrigerating apparatus



March 12, 1940.

G. W. WOLCOTT REFRIGERATING APPARATUS Filed July 9, 193m NVENTOR. .W

ATTORNEYS Patented Mar. 12. 1940 UNITED STATES PATENT OFFICE REFRIGEBATING APPARATUS Application July 9, 1937, Serial No. 152,788

2 Claims.

This invention relates to refrigerating apparatus and more particularly to means for con-' trolling the loading and unloading of compressors. In order to employ a relatively small, e'ftlcient 5 motor it is desirable to provide a compressor with an unloader. Many of such unloaders have been in the past rather complicated.

It is an object of my invention to provide an extremely simple loading and unloading means to for a compressor which will be operated by the pressure upon the suction side of the compressor.

It is another object of my invention to provide a means for controlling the-loading and unloading of the compressor which also acts as 115 a check valve upon the suction side of the compressor.

It is still another object of my invention to provide a combined piston valve and check valve upon the suction side of a compressor for con- 2g trolling the loading and unloading of a compressor.

-Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanygg ing drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

Fig. 1 is a sectional view of a motor-compressor unit taken along the line i- -l of Fig. a, together go with a diagrammatic representation of the re maining e1 .t-ents oi a refrigerating system; and

Fig. 2 is a sectional view taken along the line 3-2 of Fig. l.

Briefly, 1 have shown a refrigerating system ingg eluding a sealed motor-compressor unit having anelectric motor directly connected to a rotary compressor of the eccentric type. In this compressor, the inlet of the compressor is provided with a piston valve which covers the suction inlet. This my piston valve is provided with a valve needle for closing an unloading passage when the piston valve is forced open by the pressure difierential createdby the operation of the compressor. The piston valve, when sumcient pressure difierential 4 5 exists, opens a port and permits the feeding of the gas to the compressor inlet.

Referring now to the-drawing and more particularly to Fig. 1, there is shown a sealed motorcompressor unit it comprising a lower casing 50 member 22 and an upper casing member t l which are welded together at the joint 26. Within the lower casing member 22,- three supporting lugs it are welded to its inner walls in a 1" I etrical evenly spaced arrangement. These lugs are pro g5 vided with studs 80 which are provided for tas- (Gil. 230-24) tening a casting 32 in place. This casting 32 forms the framework 3t for the stator of the motor and an outer housing 36 for the compressor proper. The framework 34 is connected to the housing 36 by web portions 38. Extending up- 5 wardly from the housing portion 36 is a bearing support Ml provided with a bearing bushing 32.

This bearing bushing 62 receives the motor shaft M, the upper end of which receives an inverted cup-shaped mer'nber it upon which the rotor 48 10 of the motor is fastened. The rotor 38 surrounds the bearing bushing 42 while the connectingmember t6 between the rotor t8 and the shaft M is up above the bearing M. The stator 50 is held by the framework portion 34 of the casting i5 32.

The compressor proper is located within the housing ttand is provided with a top plate 52 which is fitted into a countersunk portion in the housing and sealed by a lead gasket h t. This top 2 plate 52 is also provided with a bearing 56 for the shaft l l. Beneath the bearing 56 the shaft Mi is provided with an eccentric 5B which is surrounded by a leaded bronze bushing 60 which in turn is fitted tightly into a roller member 52. Surrounding the roller 62 is the inner compressor housing ti provided with a slot which receives the divider block 66 shown in Fig. 2. This divider block is recessed to receive a spring 68 which holds it in engagement with the roller 62. $0

When the motor operates, the eccentric causes the roller to be revolved with its periphery almost in contact with the inner wall of the inner housing t l.

The shaft il l with its eccentric portion 58 rests M upon an inner bottom plate 10 which also sup:

ports the roller 62. An outer bottom plate 12 holds the inner bottom plate It tightly against the bottom face of the inner housing 64. Aspiderlike ring member it holds the outer bottom plate in place and in turn is fastened to the outer compressor housing 36 by cap screws it. Both the inner bottom plate it and the outer bottom plate it are provided with the inlet passage 80. This inlet passage passes through the inner bottom plate directly to one side of the divider block 66. The top plate 52 is provided with a discharge port 62 and a discharge valve 8t directly on the op posite side of the divider block from that of the inlet port 8%. i

In order to reduce the load upon a compressor during the starting period so that a smaller highly emcient motor with a low starting torque may be used, I provide a small unloading passage 88 which extends through the outer compressor on the outer bottom plate 12.

piston, when the compressor is idle, covers the inlet opening 96 in the outer bottom plate 12. A gasket 98, preferably formed of a rubber-like product, containing a polymer of chloro-2-butadiene-1,3 is provided in the bottom of the recess 94 for the piston 92 to rest upon. This provides a seal for the piston.

The piston 92, when the compressor is not in operation is held in sealing engagement with the gasket 98 by a light compression type coil spring I92 so that it prevents any gas from entering the inlet 96. Thus, during any idle period the gas in the sealed unit housing 20 can enter the unloading passage 88 and flow into the compressor inlet passage 80. In this way, when the compressor starts it is provided with high pressure gas at the same pressure at which it discharges a gas so that the compressor starts in an unloaded condition.

The unloading passage 88, however, is extremely small in comparsion with the capacity of the compressor, and the compressor soon creates a much lower pressure within the inlet passage 80. In a short time it reduces the pressure in the inlet passage below the pressure existing below the piston 92 in the opening 98' so thatthis pressure in the opening 96 forces the piston 92 unloading passage 88. At the same time the piston 92 uncovers a port I84 provided in the walls of the recess 94 so that the gas may pass from the opening 66 into the inlet passage 89 of the compressor. The piston 94 is rather large in area and only a slight restriction is required in the port I04 to keep the piston 92 in its uppermost position closing the unloading passage 98. The needle valve spring 9I will keep the needle valve 99 tightly against its seat during the normal nmning period even though the piston may fluctuate or vibrate slightly.

After the unloading passage 88 is closed, the compressor draws gas through the opening 98 and the inlet passage 80 in the normal manner. The gas is discharged through the discharge opening 82, the discharge valve 84, and thence: through an opening Hi6 from the outer compressor housing 36 into the interior of the sealed.

' I I2 where the compressed refrigerant is liquefied and collected in a receiver'IH. From the receiver the liquid refrigerant is forwarded through a supply conduit I I-6 to athermostatic automatic expansion valve II8 which controls the flow of refrigerant into the evaporating means I29. The refrigerant evaporates within the evaporating means I20 under reduced pressure and is returned to the compressor through a suction conduit I22 which connects with the inlet opening 96 of the compressor. The electric motor which drives the compressor is controlled by a low pressure switch means I24 which is provided with an operating bellows I26 connected by tubing I28 to the suction conduit I22.

I find that this type of system is particularly useful where it is desired to prevent high pressure gas from entering the evaporating means during the off cycle and where an unloading means is employed. It is particularly useful when used in a refrigerating system of rather small capacity which operates at a high back pressure. For example, this system is particularly useful when used for cooling drinking water, particularly when sulphur dioxide or methyl chloride are used as refrigerants in the system. In this system as soon as the compressor stops the piston valve 96 moves to a closed position 1111 der the influence of the spring I02. This prevents any gas from passing back to the return conduit into the evaporating means during the of! cycle. The piston valve 92 remains in this position until the compressor starts. During this ofi cycle high pressure gas passes through the unloading passage 88 into an inlet passage 50 that the compressor may start with equal pressures upon its inlet and outlet sides.

When the compressor starts, it gradually reduces the pressure within the inlet passage 80 until the pressure is less than the pressure within the inlet 96. Then the piston valve 92 is raised by the excess in pressure in the opening 96 and the needle valve 90 is moved upwardly to a position where it closes the passage 88. The

raising of the piston valve 92 uncovers'the port I94 and permits the gas to flow from the evaporator I28 to the inlet passage 80' of the compressor. The piston valve 92 is sufficiently large in area so that only a small throttling link effeet at the port I94 is necessary to keep the piston valve 92 in its upper position. The unloading passage 88 is suiiiciently small in comparison with the pumping capacity of the compressor that the gas pressure within the inlet passage 80 may be rapidly reduced at the start of each cycle, after which the piston closes the unloading passage and opens the portI04.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it'is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A compressing means having an inlet and an outlet, said compressing means being provided with a restricted unloading by-pass passage .connecting the inlet and the outlet, a check valve for closing the inlet, a by-pass valve for closing said unloading pas'sagefand a resilient operating connection between said check'valve and said by-pass valve for operating 'said bypass valve by the movement of the check valve. 2. A compressing means having an inlet and an outlet, a. check valve for'closing said inlet, said compressing means being provided with a restricted unloading by-pass passage extending from the portion of low side of said compressing means between said check valve and said inlet to said compressor outlet, and a by-pass valve operated by said check valve for closing said unloading passage.

, GLENN WIWOLCOTI. 

